JPS6038983B2 - Method and device for applying coating material to the outer peripheral surface of a columnar substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for uniformly applying a paste-like coating to the outer peripheral surface of a columnar substrate. This provides an effective means for uniformly applying the coating.

For example, as shown in FIG. 1, the photosensitive drum described above is made of an aluminum drum 1 with a diameter of 6 ribs, a length of 30 ribs, and a wall thickness of 5. layer 2
is formed by vapor deposition, and then a polyvinyl carbazole layer (hereinafter referred to as PVK layer) 3, which is an organic semiconductor, is formed by about 15r.
It has a structure in which it is applied uniformly to a film thickness of .

Furthermore, in an electrophotographic apparatus, it is well known that in order to obtain uniform photographs, it is necessary to uniformly charge the photosensitive drum.

Therefore, when the relationship between the film thickness of the PVK layer 3 and the charging potential with respect to the drum 1 is investigated, the result is as shown in FIG. 2. Figure 2 shows
This figure shows the relationship between the thickness of the PVK layer 3 and the charging potential, and shows that the charging potential changes very sensitively as the thickness changes.

Due to the characteristics of the electrophotographic camera, the thickness of the PVK layer 3 is approximately 15 to 20 mm.
It is preferable to have a peak, and the allowable amount of film thickness is about ±10%, that is, when the ultimate thickness is set to = 20〃, the film thickness change = ±2
It was extremely tough. Here, conventional PVK
The coating method is shown in FIG. An aluminum drum 4 having a selenium layer deposited thereon is mounted perpendicularly and in the same direction as the fixture 6 by competing with the upper end 7 of a cylindrical fixture 6 attached to the base plate 5. On the other hand, the coating jig 8 is supported by a slide post 9 in the same manner as the fixing jig 6, and can be moved in the direction of the drum 4 (arrow F) by moving on the slide post 9. . Liquid PVKI Kawama, solid PVK to organic solvent at a volume ratio of approximately 5
A liquid coating material having a viscosity dissolved in 1:1 is supplied by a boat 11 to a U groove 12 provided in a coating jig 8, and is coated on the outer surface 13 of the drum 4. Then, the excessively applied liquid PVKIO is squeezed by the ring-shaped scraping blade 14 having a certain gap with the drum 4 as the coating jig 8 moves in the downward direction of the arrow on the slide post 9, resulting in a constant film thickness. A liquid PVK layer 15 having the following properties is formed. Since the liquid PVK layer 15 is a thin film of approximately 100 mm thick, the organic solvent evaporates and solidifies in a few minutes even when it is naturally dried.

However, in the above conventional method, liquid PV
In order to keep the change in the thickness of the K layer 15 within an allowable range, extremely high concentricity is required between the drum 4 and the coating jig 8, especially the scraping blade 14.

FIG. 4 shows the relationship between the shaving blade 14 and the PVK film thickness after coating. The excessively adhered coating material 16 is squeezed through the tapered portion 17 by the parallel portion 18 with a clearance t, = (for example, 240 French), and the coating material has a liquid film thickness t2 = t, which is approximately 1/2 of the clearance t. /2=120r
It is applied as.

Furthermore, if the dilution is y by drying (for example, y=6)
, a solid film with film thickness=t2/y=20A is obtained. The relationship between the aforementioned concentricity and this solid film is shown in FIG.

The inner radius of the scraping blade 14 is r, and the outer radius of the drum 4 is r.
2=r, 10t, and their respective center positions o and o' are S
Suppose there is a shift. At this time, the maximum and minimum clearances maXt and min between the scraping blade 14 and the drum 4 are t, min, respectively.
maX=t, 10S, t,min=LS. As explained in FIG. 4, the solid coating film 15 formed by moving the coating jig 8 in the axial direction of the drum 4 through such a gap is uniform in the axial direction and has no uneven film thickness in the circumferential direction. The maximum and minimum film thicknesses are t3maX=t, 10S/2y, and t3m, respectively.
in=t,1S/2y et al=t3MX-et min=S/
It becomes y. If t3 is 4 Buddhas that are 10% of the soil with an average film thickness of 201, then y = 6, S = y t3 = 6 x 4 =
The total number of degrees is 24 Buddhas, and it is required to set the same degree, which is extremely strict and must be 24 Buddhas or less.

The following factors can be cited as causes for worsening the degree of D between the drum 4 and the scraping blade 14.

[1' Concentricity between the upper end 7 of the fixed pick-up tool 6 and the application jig 8.

'2' Parallelism of slide post 9. [3' Straightness of drum 4.

■ The inner and outer diameters of drum 4 are the same.

'5} The difference in D is due to the clearance required for the inner lining accuracy of the drum 4 and the iron fitting with the upper end 7 of the fixing jig.

'6} Inclination due to drum 4 setting error. Considering these cumulative errors, high precision is required for the coating device, drum processing precision, and setting precision, and it is extremely difficult to manufacture photosensitive drums that satisfy these conditions, and there are many problems with manufacturing processes. It had become. The present invention has been made to eliminate such drawbacks, and will be described below with reference to FIGS. 7 to 9 showing embodiments thereof.

That is, the aluminum drum 1 is supported by two bearings 20 and 21 attached to a horizontally installed base 19.
The support jig 22 fixed with the motor 2
3, the drum 1 is rotated via the belt 24.

In addition, 25 is, in order to reduce the rotational runout of the drum 1,
This jig is supported by a fixed center 27 attached to a fixed center stand 26, and also serves as a dummy part of a drum necessary for the coating process described later. On the other hand, the application pick-up tool 28 is
Due to the static air bearing effect described below, it floats concentrically above the drum. In the static air bearing, air is pumped at about 3 atmospheres from a boat 33, accumulated in an air reservoir groove 34 machined in the same shape, and then passed through nozzles 3 and 5, each of which has 12 radial throttle holes. Therefore, it is injected onto the bearing surface 36. The injected compressed air is discharged to the outside through the bearing surface 36, stored in the discharge air reservoir groove 37, and discharged to the outside through boats 38 raised at four radial locations. Therefore, the exhaust air reservoir groove 37 exhibits a value close to atmospheric pressure. Due to the above-described static air bearing, the coating jig 28 is firmly fixed to the drum 1, and the drum 1 and the coating pick-up device 28 have extremely good homogeneity.

On the other hand, numeral 39 is a support plate for the coating jig 28, and compressed air is fed under pressure from the boat 40 at four locations.
A thrust air bearing 41 is set between 8 and 8 to push the application jig 28 in the axial direction in a non-contact and low friction state. Similarly, compressed air is sent under pressure from the boat 53, and an air bearing is formed between the stopper 42 attached to the support plate 39 and the stopper 43 attached to the coating pick-up tool 28 to prevent rotation of the coating jig 28. The contact maintains low friction. The coating jig 28 is structured so that it cannot be prevented from moving in the radial direction by these support plates and stoppers. The support plate 39 is the drive source 4
4 is moved in the direction of arrow G, and the support plate 39 is structured to move the application pick-up tool 28 in the vertical direction via a thrust air bearing 41. On the other hand, PV
The K coating material is collected in a concentrically formed coating material reservoir groove 47 from the boat 46, and is excessively applied to the surface 48 of the drum 1 here.

As mentioned above, the excessively applied PVK coating passes through the tapered part 49 by moving the coating jig 28 in the direction of the axis (arrow G), and is removed by the scraping blade parallel to the axis. The structure is such that it is scraped off by a coating material with a uniform thickness. Next, the effect will be explained. It was previously explained that the accuracy of the coating film thickness of PVK coating depends largely on the concentricity of the drum 1 and the scraping blade 50, and a deviation in the concentricity results in non-uniformity of the film thickness. In this apparatus, the application jig 28 is moved using the outer surface of the drum 1 as a reference surface, using the static air bearing effect.
It is floated above the drum 1. This static pressure air bearing has a rigidity K of MT1 (mechanical.
technology. When calculated according to the design method of (Incorporated), K=2.7k9/French m.

That is, assuming that the weight of the application jig 28 is 2k9, the eccentricity S due to this weight is about 0.74v, and extremely good concentricity is obtained. In addition, the natural frequency f of this bearing is: f = health = 28 × sheep 1 pi = 3.64 × 1 pi Hz = 3.64 KHz For vibrations of the drum 1 that are sufficiently smaller than 3.64 KHz, coating treatment is required. The tool 28 follows sufficiently and does not cause gap fluctuation.

(The rotation speed of drum 1 is sufficiently small at about IR.P.S.)
Fig. 9 shows a static air bearing that uses self-generated orifices with 12 nozzles, but it may have 8 nozzles or 6 nozzles, and the nozzles may be set arbitrarily. It may also be a static air bearing such as a diaphragm, a porous diaphragm, or the like.

The reason why a static air bearing is used is to avoid contaminating the outer surface of the drum 1. The bearing surface 36 of static pressure air and the scraping blade 5 are machined with concentricity, and under the condition that the bearing surface 36 maintains high precision concentricity with the drum 1, the scraping blade 50 The same 0 degree angle as drum 1 was maintained, resulting in an extremely uniform PVK coating. The clearance of the static pressure air bearing (Cr = 20 French) is the clearance of the scraping blade 50 (
Compared to C = 200 French), it is set extremely small.
This is to increase the rigidity of the hydrostatic air bearing, and as long as the rigidity is sufficient, the same clearance may be used. Furthermore, the clearance of the wall 51 that partitions the discharge air reservoir groove 37 and the coating material reservoir groove 47 is also made as small as 30 mm, so that the coating material in the coating material reservoir groove 47 can enter the discharge air reservoir groove 37. The viscosity and surface tension of the coating material suppresses the leakage to a very small amount.Also, when the applicator 28 moves in the direction of the ball, there is no leakage at all. lrps
) is used to prevent the coating film 52 from dripping due to gravity until it solidifies after application, and for coating materials that harden quickly or coating materials with high viscosity and low fluidity, it is necessary to rotate the coating film 52. There's no need. Also, if there is no dripping due to gravity, it is not necessary to install it horizontally, and it may be installed vertically. Furthermore, since the bearing rigidity is extremely high, the drum 1 may swing due to rotation. The reason for providing air lubrication between the support plate 39 and the application jig 28 is to prevent the application jig 28 from moving in the radial direction due to friction, and in the above embodiment, the bearing rigidity is sufficiently high. Therefore, normal oil lubrication is sufficient.

Further, the reason why the air reservoir groove 34 is provided is to reduce the number of pressure hoses connected from the outside, and the boat 33 is supplied with air at one point.

Furthermore, the reason why the supporting jigs 22 and 25 are made equal to the outer diameter of the drum 1 is to prevent uneven film thickness from being created on the drum 1, which corresponds to the length of the coating jig 28 when starting and stopping. Furthermore, when the drum 1 is not rotated, the drum 1 does not have to be cylindrical. For example, even in the case of a square prism as shown in FIG. 10, the position of the nozzle 35 of the hydrostatic air bearing is If they are selected symmetrically like this, the scraping blade and the columnar base 1' can be set at a uniform constant gap.

Next, regarding other embodiments of the present invention, FIGS.
This will be explained with reference to Figure 2.

Structural parts that are the same as those in the previous embodiment are denoted by the same numbers and explanations thereof will be omitted.

In the embodiment described above, the coating jig 28 (54 in this embodiment) is floated by the static pressure air bearing effect, whereas in this embodiment, the coating jig 54 is formed on the drum 1 of AI. It is configured to float above the drum 1 via a hydrostatic fluid bearing 55 in which the coating material to be coated is a fluid.

The hydrostatic fluid bearing 55 is connected to the boat 5 to which the PVK coating material is supplied.
6, coating material accumulation groove 57, orifice 58, pocket 59,
It is composed of a bearing surface 601. With the above configuration, the coating jig 54 floats above the drum at a height D due to the pressure bearing effect described below.

The PVK coating material is fed under pressure from the boat 56 at a pressure of about 4 atmospheres, accumulated in the coating material accumulation groove 57, and further supplied to the pocket 59 through four orifices 68 provided radially, and then applied to the bearing surface 60.
On the other hand, it is discharged into the coating material reservoir groove 61. The coating jig 54 is strongly fixed by the static pressure bearing using this paint, and floats with extremely good concentricity with the drum 1. moreover,
Similar to the embodiment described above, PVK coating material is fed into the paint reservoir groove 47 from the boat 46 at a constant pressure slightly higher than atmospheric pressure, and the inside of the groove is filled with the PVK coating material, and the coating jig 54 is moved. It is moved in the direction of the arrow by the means 45, and as a result of this movement, the PVK coating material excessively applied on the drum 1 in the coating groove 47 is scraped off by the scraping blade 501, resulting in a uniform PVK coating film 52. It is structured to form a In the apparatus of this embodiment, the outer surface of the drum 1 is used as a reference surface, a PVK coating material is used as a lubricating fluid for a hydrostatic bearing, and the drum 1 is floated opposite to the drum 1. The reason why a coating material was used as the static pressure lubricant was to prevent contamination of the outer surface of the drum 1 due to the use of oil, etc., and since the PVK coating material has a viscosity of about 100 p.p. It can be used as a bearing lubricant for static pressure applications. The hydrostatic bearing is a normal hydrostatic bearing used in 4-pocket normal machine tools. In this example, an orifice throttle bearing is used for the hydrostatic bearing part, but a capillary throttle bearing or a constant flow type static pressure bearing may also be used.In particular, a bearing with high rigidity in a non-eccentric state is preferable, so a variable throttle bearing is used. It is even better if the rigidity is made infinite using . In addition, the hydrostatic bearing surface 60 and the scraping blade 50
are made concentrically, so that the hydrostatic bearing surface 60 is aligned with the drum 1.
Under the condition where a high precision relationship is maintained, the scraping blade 50 has the same high precision as the drum 1, resulting in a uniform film thickness.

By setting the clearance of the hydrostatic bearing to be smaller than the clearance of the scraping blade, the rigidity of the hydrostatic bearing can be increased, and the same clearance may be used as long as the rigidity is sufficient. In addition, the reason why the drum 1 is rotated is to prevent the coating film 52 from dripping due to gravity until it dries and hardens after application. For objects, there is no need to rotate them. Further, as long as there is no dripping due to gravity, it is not necessary to install it horizontally, and it may be installed vertically. Since the bearing rigidity is extremely high, the drum 1 may swing due to rotation.
The reason why air bearings are used between the support plate 39 and the application jigs 28 and 54 is to prevent the bearing effect from worsening due to friction. It can also be lubricated. The purpose of providing the Nurimura accumulation groove 57 is to reduce coupling with the pressure feed hose from the outside, and cleaning can be facilitated by removing the cover 62. As is clear from the above embodiments, the present invention provides a method for scraping off the coating material supplied to the outer peripheral surface of the columnar base by supporting the coating jig with a hydrostatic fluid bearing when scraping off the coating material supplied to the outer peripheral surface of the columnar substrate. The shape base and coating odor are the same with high precision.
This allows the coating to be applied uniformly onto the columnar substrate. In addition, especially when an air bearing is used to support the coating jig, compared to the case where a coating material such as a Cds photosensitive material is used as the fluid in the hydrostatic fluid bearing, the pressure causes deterioration of the photosensitive characteristics. This has the advantage of eliminating problems such as deterioration of the coating material, and also eliminates the problem of the coating material quickly solidifying after coating and removing the aluminum drum, blocking the nozzle hole of the hydrostatic bearing and requiring time and effort to clean it. There are advantages such as:

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a photosensitive drum, Figure 2 is a photoelectric characteristic diagram of the photosensitive drum, Figure 3 is a schematic diagram of a conventional device for forming a PVK layer on a drum, and Figure 4 is a diagram of a conventional device for forming a PVK layer on a drum. Figures 5 and 6 are cross-sectional views showing the concentricity and non-uniformity of the film thickness by the same device, respectively, and Figure 7 is a columnar diagram showing an embodiment of the present invention. A vertical cross-sectional view of a coating material application device to the outer circumferential surface of a base; FIG. 8 is a vertical cross-sectional view of an air bearing of the same device;
FIG. 9 is a front sectional view of the air bearing, FIG. 10 is a partial front sectional view of a device showing another embodiment of the invention, and FIG. 11 is a columnar base showing still another embodiment of the invention. FIG. 12 is a longitudinal cross-sectional view of an apparatus for applying a coating material to an outer circumferential surface, and FIG. 12 is a front cross-sectional view of a main part of the apparatus. 1...Drum (column-shaped base), 28, 54...
...Application pick-up tool, 45...Transportation means, 47,6
1...Coating material reservoir groove, 48...Surface (outer surface)
, 50... Scraping blade, 52... Paint film, 55... Hydrostatic fluid bearing. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] 1. A coating material is supplied to the outer circumferential surface of a columnar substrate, and a coating material scraping blade of a coating jig supported via a hydrostatic fluid bearing is applied to the outer circumferential surface of the columnar substrate. A method for applying a coating material to an outer circumferential surface of a columnar substrate, comprising scraping off the coating material supplied to the outer circumferential surface of the columnar substrate. 2. The method of applying a coating material to the outer peripheral surface of a columnar substrate according to claim 1, characterized in that an air bearing is used as the hydrostatic fluid bearing. 3. A method for applying a coating material to the outer peripheral surface of a columnar substrate according to claim 1, characterized in that a coating material is used as the fluid of the hydrostatic fluid bearing. 4. A coating jig provided on the outer circumferential surface of a columnar base via a hydrostatic fluid bearing, and a moving means for relatively moving the coating jig and the columnar base in the longitudinal direction; is provided with a groove for holding a predetermined amount of coating material and supplying it to the outer circumferential surface of the columnar substrate, and a scraping blade located downstream of this groove in the traveling direction and scraping off the coating material on the columnar substrate. An apparatus for applying a coating material to the outer peripheral surface of a columnar substrate. 5. The apparatus for applying a coating material to the outer peripheral surface of a columnar substrate according to claim 4, characterized in that an air bearing is used as the hydrostatic fluid bearing. 6. An apparatus for applying a coating material to the outer circumferential surface of a columnar substrate according to claim 4, characterized in that the fluid of a hydrostatic fluid bearing is used as the coating material.